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1.) average number of moles of NaOH dispensed 3,) Based on your coarse titration

ID: 998345 • Letter: 1

Question

1.) average number of moles of NaOH dispensed

3,) Based on your coarse titration volume, do you expect the acetic acid solution to have a higher or lower concentration than the NaOH solution?

please help with these 2 questions

Part 1: Prepare the NaOH Solution

Lab Results

How many mL of water were used to prepare the NaOH solution?

Data Analysis

Calculate the molarity of the NaOH solution. The molar mass of NaOH is 39.997 g/mol.

Calculate the amount of benzoic acid to be neutralized by 20.00 mL NaOH solution, in both moles and grams. The molar mass of benzoic acid is 122.12 g/mol.

Part 2: Perform a Coarse Titration

Lab Results

Record the following data from your course titration in the table below.

Data Analysis

How do you expect your coarse titration volume to compare to your fine titration volumes?

Part 3: Perform Fine Titrations

Lab Results

Record the volume of NaOH solution dispensed in the 3 fine titrations.

Data Analysis

Calculate the average concentration of the NaOH solution, using the average volume of NaOH solution dispensed in the 3 fine titrations. Report your answer using enough significant figures to distinguish it from the expected concentration of 0.100 M.

V = (V1 + V2 + V3) / 3

V = (20.03 mL + 20.06 mL + 20.02 mL) / 3 = 20.04 mL

M = n / V = 0.00200 moles / 0.02004 L = 0.0998 M

Learning objective: Determine the concentration of a solution.

20.21= ----> 0.0999M

Experiment 2: Use the Standardized NaOH Solution to Determine the Concentration of an Acid

Part 1: Perform a Coarse Titration

Lab Results

What was the pH at the end point of the coarse titration?

Data Analysis

Based on your coarse titration volume, do you expect the acetic acid solution to have a higher or lower concentration than the NaOH solution?

Part 2: Perform Fine Titrations

Lab Results

For the 3 fine titrations of the acid of unknown concentration, fill in the following data.

Data Analysis

Calculate the following quantities and record the data in the table below.

Conclusions

Phenolphthalein is pink over the range of pH 8 – 12. Why was it a useful indicator of when the equivalence point was reached?

Suppose a student titrated a sample of monoprotic acid of unknown concentration using a previously standardized solution of NaOH.

Given the data in the figure above, what is the concentration of the unknown acid?

0.0617M

Lab NOTES:

ex1

Take sodium hydroxide from the Materials shelf and add 0.800 g to the beaker.

Take water from the Materials shelf and add 200 mL to the beaker.

Ph 2.96

inital volume in burett

inital volume 50ml

1.) volume43.78mL

volumes dispenced =6.22ml

2. volume =38.05

volume dispenced =11.95ml

3.)volume = 32.06

volume dispenced=17.94

4.28.89ml

volume dispenced=21.11ml

ph=10.95

--------------------------------------

Ex 2

inital ph= 2.96

volume30.33

dispence 20.05

1. volume 39.92ml

volume dispenced=10.08

2.volume 29.66

voiume dispence 20.34

final ph10.43

initial valume in burett 50ml

--------------------

ex3

final ph9.43

volume 30.28

volume dipenced=20.00

----------------------------------------------------------------------

2nd Ex

initial ph 3.11

volume 50

1. volume 48.95mL

dispenced 1.05mL

ph 3.87

2. volume 45.88

dispenced 4.12

ph 4.67

3 volume 42.99

dispenced 7.01

ph 5.29

4 volume 39.93

dispence 10.07

ph 11.45

--------------------

F1

final ph 9.99

volume 59.11

dispenced 9.05

F2

ph 9.59

volume 40.97

dispenced 9.03

f3

ph 9.50

volume 40.98

9.02

1.) average number of moles of NaOH dispensed

Explanation / Answer

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